Question

(5) P-4-7 set up & solve, rate

A gold dredge is a machine that was used in the early 1900s to extract gold from a river or pond. The amount of
dirt a gold dredge can dig in 1 minute is equal to the amount it would take 3 people, each digging at the same
rate, to dig in 1 day. At this rate, how many days would it take 2 persons to dig as much dirt as a gold dredge
can dig in 60 minutes ?
A) 30 B) 45 C) 60 D) 90
Show work please.

Answer 1

D) 90 Days

Explanation:

dredge 1 min = 3 people days

when I say people days, I mean 3 people working one day

multiply each side by 60 to get the desired 60 min of dredge:

dredge 60 min = 180 people days

As we currently have this set up, it will take 180 people, 1 day to do the same amount of work as 60 min of dredge, but we only want 2 people. This means we need to divide the people days by 2 to get how many days are needed for 2 people, thus:

dredge 60 min = 2 people for 90 days